1. Field of the Invention
The invention disclosed and claimed herein generally pertains to a method that uses the loopback interface and loopback address to route datagrams or other information carrying packets in a computer system. More particularly, the invention pertains to a method of the above type wherein the computer system is divided into multiple workload partitions, and at least some of the partitions have two or more applications. Even more particularly, the invention pertains to a method of the above type wherein the loopback address is used to route packets from one application in a workload partition to a different application in the same partition.
2. Description of the Related Art
As is well known by those of skill in the art, a loopback address is a special Internet Protocol (IP) number (127.0.0.1) that is designated for the software loopback interface of a computer system. The loopback interface has no hardware associated with it, and is not physically connected to a network. The loopback interface operates on the IP network layer, or common processing layer, and enables a client and a server on the same host to communicate with each other using TCP/IP. The loopback interface also acts to prevent datagrams with the loopback address from leaving the host.
It is further well known to divide a computer system into separate partitions, wherein each partition has one or more associated applications. Different workloads are run on respective partitions, wherein strong separation is enforced between running workloads. Workload partition arrangements of this type can be very beneficial in carrying out certain tasks and applications. Moreover, applications in respective partitions may seek to use the loopback address, described above. Accordingly, the loopback address must be made available to each workload partition.
In a partitioned computer system as described above, if a datagram or information carrying packet is to be routed from a first partition to a second partition, the IP address of the second partition is applied to the packet as its destination address. The packet is then directed to the IP network layer, and processed for routing to the second partition. Similarly, if a packet is to be sent from a partition in the computer system to a location outside the system, the packet is given the IP address of the location. The packet is again sent to the IP layer initially, and then routed to the location. However, it frequently happens that a packet must be sent from one application in a partition to a different application that is located in the same partition. Applications would prefer to use the loopback address in this situation, if they could do so, as they are guaranteed to be communicating within that partition and can also assume a level of trust when using the loopback address as it is in the same partition. However, at present the loopback address is available to all partitions, so that all partitions would receive a packet that used the loopback address. To increase efficiency it would be desirable, in this case, to provide some mechanism or technique for ensuring that the packet went only to the different application located in the same partition.